<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
    </head>
    <body>
        <ul></ul>

        <script>
            var people = [
                { name: '牛油1号', id: 1, age: 20 },
                { name: '牛油2号', id: 2, age: 21 },
                { name: '牛油3号', id: 3, age: 19 },
            ]
            var ul = document.querySelector('ul');
            // 补全代码
            var str = ''
            let len = people.length
            for (let i = 0; i < len; i ++) {
                str += '<li>' + people[i].name + ' '+ people[i].age + '岁</li>'
            }
            ul.innerHTML = str
            
        </script>
    </body>
</html>